Better off with stock displacement LS2, or stroking it to 402 for twin 62mm turbos?
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Better off with stock displacement LS2, or stroking it to 402 for twin 62mm turbos?
Hey everyone, I'm hoping to get some solid advice on this. My '05 GTO recently had a custom twin 62mm turbo setup fabricated. I'm using Precision Turbo HP6265 model units, with .81 A/R exhaust housing and a T4 flange. The down-pipes and full exhaust system is 3" all the way back, with 2.5" up-pipes and 2.5" charge pipes.
I have a stock bottom-end LS2, using stock heads, but with a custom blower cam package (designed for my old Magnacharger, but still in my motor). My car dyno'd 639 rwhp at 7.91 PSI on a Dynapack dyno. This power was put out through a stalled and built 4L60E transmission. With my old Maggie setup I made 508 rwhp at 7.11 PSI on this same dyno, so this new twin turbo setup seems to be very potent.
My problem is it's time for a new motor (blown top ring land on #1 piston), and I can't decide on displacement. The stock LS2 block looks good to reuse, with just 21k on the motor also. I just need to decide if I should stick with a stock stroke crankshaft, or if a 402 stroker should do and not be too much displacement for my 62mm turbos.
I'm looking at going with a 10.1:1 compression and want to make enough power to eventually be capable of maybe some high 8-second quarter mile passes (maybe around 900 rwhp through a TH400 trans for this??) with a full-weight car (around 4200 lbs). This is years from now, but I want that to be possible. I don't want too much displacement to where my turbo's can't feed, but 402 stroker fully-forged rotating assembly package deals seem to be inexpensive, and I haven't found any stock-stroke LS2 rotating assembly packages out there.
Also, if a 402 stroker ends up being too much for my turbos would using more restrictive heads solve the problem? If so, or if not, are there any other ways to combat too much displacement of a motor in a situation like this? My setup does use stock C6 exhaust manifolds, so I wonder if that would help with making a larger displacement motor not breathe too much??
Again, any good help on this would be greatly appreciated!!! Thanks for your time!
-Andrew
I have a stock bottom-end LS2, using stock heads, but with a custom blower cam package (designed for my old Magnacharger, but still in my motor). My car dyno'd 639 rwhp at 7.91 PSI on a Dynapack dyno. This power was put out through a stalled and built 4L60E transmission. With my old Maggie setup I made 508 rwhp at 7.11 PSI on this same dyno, so this new twin turbo setup seems to be very potent.
My problem is it's time for a new motor (blown top ring land on #1 piston), and I can't decide on displacement. The stock LS2 block looks good to reuse, with just 21k on the motor also. I just need to decide if I should stick with a stock stroke crankshaft, or if a 402 stroker should do and not be too much displacement for my 62mm turbos.
I'm looking at going with a 10.1:1 compression and want to make enough power to eventually be capable of maybe some high 8-second quarter mile passes (maybe around 900 rwhp through a TH400 trans for this??) with a full-weight car (around 4200 lbs). This is years from now, but I want that to be possible. I don't want too much displacement to where my turbo's can't feed, but 402 stroker fully-forged rotating assembly package deals seem to be inexpensive, and I haven't found any stock-stroke LS2 rotating assembly packages out there.
Also, if a 402 stroker ends up being too much for my turbos would using more restrictive heads solve the problem? If so, or if not, are there any other ways to combat too much displacement of a motor in a situation like this? My setup does use stock C6 exhaust manifolds, so I wonder if that would help with making a larger displacement motor not breathe too much??
Again, any good help on this would be greatly appreciated!!! Thanks for your time!
-Andrew
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Alot depends on your budget and goals. Your stock crank will good for around 1200hp if you wanted to stay stock cubes.If you wanted to stroke it then your going to spend another $1000-$1200.00 on the crank depending on who you get it thru? I persoanlly would stay stock cubes ,save the extra money for some other upgrades, like the fuel system and larger injectors,etc.
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Alot depends on your budget and goals. Your stock crank will good for around 1200hp if you wanted to stay stock cubes.If you wanted to stroke it then your going to spend another $1000-$1200.00 on the crank depending on who you get it thru? I persoanlly would stay stock cubes ,save the extra money for some other upgrades, like the fuel system and larger injectors,etc.
For my fuel system I'm probably looking at just one more 255 lb/hr pump, some -8 or -10 line, and a regulator. Selling my new 60 lb injectors for some larger new ones won't be that expensive of a difference, so there's not much to spend in the fuel system really from here. And I already have aftermarket rails.
Saving that extra $$ for a new transmission would be wise however, but I just don't want to skimp out on the crank.
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So if I stick with stock cubes, can I just use a forged 3.662" stroke LS1 crankshaft in my LS2 block? I haven't seen any 3.662" forged cranks labeled as "LS2" cranks, but I assume the LS1 and LS2 forged cranks are the same??
And then are there any down-sides to keeping a smaller displacement motor for a setup like mine????????????????????
#7
If you are gonna replace the crank you may as well go with the bigger cubes. The stock crank is fine for up to 1200hp like stated above. Replacing the stock crank for an aftermarket stock stroke crank is pointless in a street car. Better off spending the Money elsewhere.
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#9
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If you are gonna replace the crank you may as well go with the bigger cubes. The stock crank is fine for up to 1200hp like stated above. Replacing the stock crank for an aftermarket stock stroke crank is pointless in a street car. Better off spending the Money elsewhere.
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Nevermind. K1 makes stock stroke and stroker cranks.
http://www.campbellenterprises.com/k...rankshafts.php
http://www.campbellenterprises.com/k...rankshafts.php
Yes, thanks for pushing that statement. That's definitely my biggest concern of this whole post.
Any comments on that Josh???
Thanks guys!!!
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i'm going with the K1 stuff myself.just not sure on the stroke yet couse i'm in the same boat as u i don't want to over spool my 20g turbos.my friend has had the K1 402ci kit in his ride for 2yrs at 25lbs in just checked up on the motor and said it looked new so he just buttoned it back up in called it a day
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i'm going with the K1 stuff myself.just not sure on the stroke yet couse i'm in the same boat as u i don't want to over spool my 20g turbos.my friend has had the K1 402ci kit in his ride for 2yrs at 25lbs in just checked up on the motor and said it looked new so he just buttoned it back up in called it a day
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If it were me I would reuse the crank and get good rods and pistons. There are a ton of guys making lots of power through stockish cubic inches. I'd be afraid them turbos will max out quick with a stroker motor.
You also may want more than one more walbro for your goals.
You also may want more than one more walbro for your goals.
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If it were me I would reuse the crank and get good rods and pistons. There are a ton of guys making lots of power through stockish cubic inches. I'd be afraid them turbos will max out quick with a stroker motor.
You also may want more than one more walbro for your goals.
You also may want more than one more walbro for your goals.